1. Field of the Invention
The present invention relates to a method for transferring superfine photoresist structures into a dielectric layer by means of selective ion bombardment.
2Description of the Prior Art
In the manufacture of semiconductor components, fine structures having minute structural dimensions and tolerances on the order of magnitude of 0.1 micron must be generated in a dielectric layer. For this purpose, a photoresist mask is usually applied to the dielectric layer to be structured. The structures of the photoresist mask are then transferred geometrically in precise form to the dielectric layer to be structured. Frequently, an oxide layer and/or a nitride layer are employed as the dielectric layer to be structured.
In previous methods for transferring superfine photoresist structures into a dielectric layer, the geometric precision of the structure transferred onto the etched, dielectric layer was unfavorably influenced because of a poor adhesion of the photoresist to the dielectric layer. In the known methods for transferring superfine photoresist structures into a dielectric layer, the width of the lateral undercutting was equal to the thickness of the etched dielectric layer even with ideal adhesion of the photoresist to the dielectric layer.
In previous methods for transferring superfine structures, the narrowest possible strips in the photoresist structure were imaged onto the dielectric layer to be structured. In these known methods for transferring superfine photoresist structures, however, these very narrow strips were still too wide for microwave transistors. As a result of heating the photoresist mask at temperatures of 100.degree. C. to 140.degree. C., the strip width to be imaged onto the dielectric layer to be structured becomes smaller in the structure of the photoresist mask in that the edge regions of the photoresist mask run together. This procedure of converging the edge regions of the photoresist mask must be terminated at the desired strip width in the structure of the photoresist mask. The speed at which the lacquer bleeds, however, cannot be predetermined. Repeated interruptions with optical control of the strip widths in the structure of the photoresist masks on the semiconductor wafers are therefore necessary during the bleeding of the lacquer. When the desired strip width in the structure of the photoresist mask is not achieved during the lacquer bleeding, the photo technique in which the photoresist mask is structured must be repeated.
The lacquer bleeding for diminishing the strip width in the structure of the photoresist mask on a semiconductor wafer does not occur with three-dimensional uniformity. Great manufacturing tolerances must therefore be accepted in the manufacture of solenoid conductor components with the employment of known methods for transferring superfine photoresist structures.